This invention relates to an endless belt for transmission employed in a belt-type stepless transmission used in automotive vehicles and the like, in which an endless belt is stretched between an input pulley and an output pulley and stepless shifting is performed by varying the radius of the position of frictional engagement between the endless belt and the input and output pulleys.
Stepless transmissions have been developed in order to facilitate driving and obtain a comfortable driving feeling in automotive vehicles.
One example of such a stepless transmission that has been conceived is a belt-type stepless transmission which relies upon an endless belt. The belt-type stepless transmission is so adapted that an input pulley disposed on the output-shaft side of a starting device and an output pulley disposed on the output-shaft side of a transmission are connected by an endless belt. The position of frictional engagement between each pulley and the endless belt is suitably controlled to continuously vary the transmission (gear) ratio, thereby accomplishing shifting in stepless fashion.
One example of an endless belt employed in such a belt-type stepless transmission is as disclosed in the specification of Japanese Patent Application Laid-Open (KOKAI) No. 63-115939. The disclosed stepless belt includes a number of flat plate-shaped blocks which frictionally engage input and output pulleys, a number of link pieces which pass through holes in the blocks and are endlessly connected by pins, and a member which prevents the pins from slipping out of the link pieces.
The endless belt comprising the number of blocks is such that at the time of power transmission, power is transmitted from the input pulley to the block pieces which frictionally engage the input pulley. The power transmitted to the block pieces is transmitted to the output pulley via the link pieces and the blocks frictionally engaged with the output pulley. In this case, a stepless shifting operation is performed by so executing control as to continuously vary the rotational radius of the position of engagement between the input pulley and the blocks and the rotational radius of the position of engagement between the output pulley and the blocks.
When the blocks frictionally engage the input and output pulleys at power transmission in this disclosed endless belt, or when the blocks or disengaged from the input and output pulleys, the load applied to the blocks changes, causing neighboring blocks to collide with each other. Such collision produces vibration and noise. In particular, since the blocks generally are made of metal and the endless belt is rotated at comparatively high speed, the sound of neighboring blocks colliding is very loud and unpleasant.
In addition, the blocks themselves vibrate at engagement and disengagement of the blocks and input and output pulleys, and this vibration is also a source of noise.